Stretching method and apparatus

ABSTRACT

A carpet stretching assembly is disclosed which includes a ladder-type mounting structure engaged by releasable stretching member. The stretching member are actuated by a hydraulic ram or ratchet jack to engage the mounting structure and thereby apply force to stretch a carpet via a gripping head assembly which engages the carpet. The stretched carpet is held in its stretched condition by positioning carpet holding member to engage the mounting structure and grip the carpet by a gripping head assembly.

BACKGROUND OF THE INVENTION

This invention relates to apparatus for stretching or tensioningsheet-like material such as carpet and to methods of stretching ortensioning such material.

This invention has particular but not exclusive use to the stretching ofcarpets, and for illustrative purposes reference will be made to suchapplication. However it will be understood that this invention could beused in other applications where the stretching or tensioning ofsheet-like material is required and references herein to "carpet" are tobe construed as including reference to other sheet-like material.

DESCRIPTION OF THE PRIOR ART

Known carpet stretching equipment includes an extendable pole or supportrod to which is attached a carpet gripping head or stopper. One end ofthe support rod is positioned against a wall of the area to be carpetedwith the other remote end carrying the gripping head or stopper whichgrips the carpet with a large number of downwardly projecting spikes.The carpet is stretched by the application of force or pressure to thegripping head so as to cause the gripping head to move relative to thesupporting pole. This arrangement is used for domestic installations aswell as for large scale commercial installations. In practice the lengthof carpet runs which may be efficiently stretched by this method islimited to lengths of about twenty meters. Thus, where an extendedlength of carpet such as sixty or eighty meters is to be laid incommercial or industrial applications, the carpet must be stretched tothis shorter distance and then tacked down or stay-nailed intermediateits length. The stretching equipment is then repositioned or extendedand the stretching operation recommenced.

It is also necessary with existing arrangements for the stretchingoperation to be carried out repeatedly across the width of a carpet.This adds considerably to the time and effort required to lay thecarpet.

Another disadvantage associated with the existing stretchers occurs whenseparate lengths of carpets are joined by applying a heat activatedthermoplastic adhesive tape to adjoining seams o the carpet. Because theadhesive tape is not meant to be stretched, it is important that thelengths of carpet to be joined are equally stretched before applicationof the tape. As the requisite equal stretching is very difficult toachieve, joints often fail by cupping and breaking of the adhesive bond.

The current methods are time consuming and do not enable carpet to bestretched uniformly across its length and width. Consequently it isdifficult with existing equipment to meet required standards when layingcarpet, although experienced and skillful layers are able to approximatethe standards required. Nevertheless it is not uncommon for bubbling andpremature wearing to occur.

This invention aims to alleviate at least one of the above mentioneddisadvantages and to provide stretching apparatus which will be reliableand efficient in use. Other objects and advantages of this inventionwill hereinafter become apparent.

DESCRIPTION OF THE PRESENT INVENTION

With the foregoing and other objects in view, this invention in oneaspect resides broadly in a carpet stretching assembly including;

an elongate mounting structure having a ladder type frame adapted torest stably upon a carpeted surface;

anchoring means associated with said mounting structure;

releasable stretching means engageable with said mounting structure andoperable to stretch carpet from a selected portion thereof in thelongitudinal direction of said mounting structure, and

carpet holding means engageable with said mounting structureintermediate said stretching means and said anchoring means.

Preferably the mounting structure includes a plurality of scaffoldframes adapted for assembly in end to end relationship. It is preferredthat the mounting structure is constructed from aluminium or other lightweight material having the required strength characteristics. It is alsopreferred that the width of each module of the mounting structure andthe length thereof be such as will facilitate ready access by stairs,lifts, doors etc to areas where carpet is being laid.

The releasable stretching means and/or the carpet holding means mayinclude any suitable arrangement whereby a carpet or the like may begripped or otherwise firmly held with the grip not being broken by theapplication of pressure thereto. They could for example include an edgegripping device with a frictional gripping action. However it ispreferred that the releasable stretching means and/or said carpetholding means includes a gripping head assembly adapted to releasablygrip the carpet. Suitably the gripping head assembly includes at leastone gripping head having an array of inclined spikes projectingdownwardly therefrom. It is preferred that the gripping head assemblyincludes at least three said gripping heads arranged such that one saidgripping head is positioned centrally of said mounting structure and theother said gripping heads are respectively positioned transversely oneither side thereof.

The releasable stretching means and/or said carpet holding means mayinclude actuating means adapted to move said gripping head assemblyrelative to said mounting structure. The actuating means could forexample be remote controlled and servo driven or could be manuallyoperable. Suitably the actuating means includes a ratchet mechanism or ahydraulic jacking mechanism.

The releasable stretching means may be fixedly mounted to the mountingstructure by separately attaching a portion of the stretching means tothe frame so as to permit the member carrying the gripping heads to bemoveable relative to the fixedly attached portion. Alternatively thereleasable stretching means may be movably mounted on the mountingstructure by means of wheels or runners adapted to enable the stretchingmeans to move along the mounting structure.

In a preferred embodiment the releasable stretching means and/or saidcarpet holding means includes:

a frame supporting said gripping head assembly,

conveying means on said frame whereby said releasable stretching meansand/or said carpet holding means is moveable relative to said mountingstructure, and

abutment means engageable with corresponding abutment means on saidmounting structure whereby said releasable stretching means and/or saidcarpet holding means is engageable with said mounting structure.

Suitably the conveying means includes a plurality of wheels mounted onsaid frame and adapted to transport said releasable stretching meansand/or said carpet holding means across the carpet and above and alongsaid mounting structure, and said abutment means includes at least onetransversely extending face adapted to engage a transversely extendingmember on said mounting structure.

The stretching assembly may include calibration means whereby the degreeof stretch may be determined and monitored. The calibration means may beconnected to a print-out device to provide a printed record.

The anchoring means may be a gripping head assembly adapted toreleasably grip the carpet or it may be an abutment adapted to abut awall or the like at which the carpet is secured. Preferably the abutmentmeans is an end of said mounting structure.

In a further aspect this invention resides broadly in a method ofstretching laid carpet, said method including:

arranging an elongate mounting structure on the laid carpet;

anchoring said mounting structure relative to the laid carpet;

releasably connecting stretching means to said mounting structurewhereby carpet may be stretched away from said anchoring;

actuating said stretching means to stretch a first portion of the carpetin the longitudinal direction of said mounting structure;

connecting holding means to said mounting structure at a first holdingposition intermediate said stretching means and said anchoring wherebythe stretched first portion of carpet is maintained in a stretchedstate;

releasably re-connecting said stretching means to said mounting meansbeyond said holding means whereby carpet may be stretched away from saidholding means;

actuating said stretching means to stretch a further portion of thecarpet in the longitudinal direction of said mounting structure, and

re-connecting said holding means to said mounting structure at a secondholding position intermediate said stretching means and said firstholding position whereby the stretched further portion of carpet ismaintained in a stretched state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a stretching assembly with one form of releasablestretching means attached to a mounting structure;

FIGS. 2-4 illustrate alternative forms of a releasable stretching meansin accordance with the invention;

FIG. 5 illustrates one form of a carpet holding means;

FIG. 6 illustrates a pole-like mounting structure with stabilisingmeans, and

FIGS. 7(a) to 7(e) illustrates the stages in using the carpet stretchingassembly in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

As can be seen in FIG. 1, the stretching assembly includes releasablestretching means 11 fixedly attached to the module 51 of a mountingstructure. The releasable stretching means has three gripping heads 12attached to a crossbar 13 by means of spigot mounts 14. The spigotmounts 14 are retained in the crossbar 13 by latches (not shown). Thecrossbar 13 may be selectively urged away from the mounting frame module51 by ratchet jacking mechanisms 15, 16 fixed to the leading crossbar 18of the mounting frame 51 with the ratchet housings 16 welded orotherwise affixed to gusset plates 17 welded to the crossbar 18. Anadditional central slide mounting 22 is provided by an elongate rod 24attached to the crossbar 13 being slidably received in a cylindricalhousing 23 affixed to a transverse rung 53 and the leading crossbar 18of the module 51. The slide mounting 22 assists in maintainingstructural integrity between the mounting frame module 51 and thecrossbar 13. The jacking mechanisms 15, 16 are operated by a commonactuating lever 21 connected to the jacking mechanisms by yoke 20whereby each end of the crossbar 13 is simultaneously advanced. Releasemeans 19 are provided to release the jacking mechanisms so that thegripping heads may be disengaged from the carpet.

The mounting frame module 51 has sockets 54 at one end of the side rails52 for receiving the other male ends 55 of the side rails of aconventional aluminium scaffold frame 61 whereby the effective length ofthe mounting frame may be increased step wise by selectively addingfurther scaffold frames 61 in end to end relationship to the mountingframe. In this manner readily available scaffold frames 61 may beobtained to increase the effective length of the mounting frame to anydesired length. The male ends 55 are a relatively loose fit whereby themounting frame may be pivoted upwardly with respect to the connectedscaffold frames 61 to enable the gripping heads to be raised for releasefrom the carpet.

As can be seen in FIG. 2, the releasable stretching means 30 includes apair of hydraulic rams 32 arranged to advance the gripping heads 12. Thehydraulic rams have pistons 33 fixedly attached to the leading cross-barmember 13 with the cylinders 32 being affixed to a second and trailingcross-bar member 37. The hydraulic rams 32 include actuating or pumpinglevers 3A adapted to incrementally advance the pistons 33 by repeatedoperation thereof.

Each of the cross-bar members 37 and 13 have a pair of concave wheels 35mounted thereon to be complementarily engageable with and able to runalong the parallel side members 52 of the mounting frame. The wheels 35are mounted at a slight angle to the vertical such that the stretchingmeans is able to freely track along the side members 52.

As can be seen in FIG. 2, the gripping heads 12 have an array offorwardly inclined depending spines 31 for engaging and gripping thecarpet in a conventional manner.

The stretching means 30 illustrated in FIG. 2 thus comprises atrolley-like assembly adapted to move freely along an extended mountingframe. The cross-bar member 37 carries a pair of pawls 36 hingedlyconnected thereto whereby they may pivot rearwardly to enable thestretching means 30 to pass across the transverse rungs 53 of themounting frame and to rest in front of the rung to form an abutmentagainst which the stretching means abut when the hydraulic rams 32 areactuated.

The releasable stretching means 70 illustrated in FIG. 3 has asupporting frame 71 mounted on wheels 75 such that the stretching means70 is able to travel along the laid carpet over the mounting frame 61 asthe wheels 75 track along the carpet outside the side rails 52 of themounting frame 61. The supporting frame 71 has a pair of side members 72supporting a leading cross member 74 and a trailing cross member 73. Thewheels 75 are pivotally mounted at respective ends of the cross members73 and 74. The trailing crossmember 73 supports a hydraulic fluidreservoir 82 from which hydraulic fluid is pumped to a hydraulic jack 76via suitable hosing 83 by the action of pump handle 84. The hydraulicjack 76 is cradled in a supporting arm 77 pivotally mounted on thetrailing cross member 73 to rotate about a transverse axis. A mountingstructure engagement bracket 87 depends from the supporting arm 77 so asto be engageable with a transverse rung 53 of the mounting structure 61in a lowered position of the supporting arm 77. The hydraulic actuatedpiston 78 is attached to a cross bar 79 which carries three conventionalgripping heads 80. Bowing of the cross bar 79 is prevented by atensioning brace 81 welded to the ends thereof and separated therefromin the central region by struts 88. The gripping head assembly can beraised to an elevated position at which the gripping heads 80 clear thecarpet, or can be lowered to a carpet engaging position by the action ofa lifting handle 85. The lifting handle 85 is operable through a seriesof linkages 86 to retain the elevated head assembly in stableequilibrium in an over-centre position.

In use the releasable stretching means 70 is rolled along the carpetover the mounting structure and when positioned at an appropriatelocation to commence stretching the carpet, the cross member 79 andassociated gripping heads 80 is lowered to engage the carpet by loweringthe lifting mechanism 85. When pressure is applied by pump handle 84 tomove the stretching means, the engagement of the gripping heads 80 withthe carpet causes the stretching assembly 70 to roll backwards on wheels75 until the mounting structure engagement bracket 87 bears on and isrestrained by a transverse rung 53 on the mounting structure 61. Furtheractuation of the pump handle 84 causes the carpet to be stretched.

The releasable stretching means 100 as seen in FIG. 4 is substantiallysimilar to that illustrated in FIG. 3 except that a pair of transverselyspaced hydraulic jacks 101 are provided instead of a central jack.

It will of course be obvious that the various stretching meansillustrated in FIGS. 1 to 4 are completely interchangeable in as much asthe hydraulic embodiments illustrated in FIGS. 2 to 4 could include thearrangement of permanent affixing of one portion of the stretching meansto the mounting frame, whilst the ratchet mechanism illustrated in FIG.1 could also be mounted on wheels to provide a trolley-like stretchingmeans.

In an alternative embodiment (not illustrated) the arrangement shown inFIGS. 3 and 4 is varied so that the gripping head assembly is positionedahead of the leading edge of the wheeled support frame thereby enablingthe gripping head to abut a wall or skirting board against which thecarpet is to be fixed.

FIG. 5 illustrates a carpet holding means 111 by means of which carpetstretched by the releasable stretching means is maintained in itsstretched condition. A cross bar 112 supports three gripping heads 113in transverse spaced relation similar to the gripping head assembly ofthe releasable stretching means. A pair of transversely spaced abutmentfaces 115 depend from the crossbar 112 and are spaced to abut atransverse rung 53 of the scaffold frame 61. The cross bar 112 alsosupports a pair of wheels 116 and an upwardly extending handle 114.

In use, the carpet holding means 111 is positioned behind a releasablestretching means such that the abutment faces 115 abut a transverse rung53 of the scaffold frame 61. When the releasable stretching means isreleased, the stretched carpet is maintained in its stretched conditionby the gripping action on the carpet of the holding means 111. When thereleasable stretching means is re-positioned and the carpet restretchedto its new position, the carpet holding means 113 can be disengaged fromthe carpet at its first position by pivoting the handle 114 forward sothat the holding means 111 pivots on the wheels 116 thereby raising thegripping heads 113 and disengaging them from the carpet. The carpetholding means thus clears the mounting structure and is then rolledalong the carpet over the mounting structure to its new holding positionadjacent the re-positioned stretching means.

As seen in FIG. 6, the mounting structure may include a number ofelongated rods 132 adapted to interlock to form an extendable pole-likeassembly 131 adapted to carry a releasable stretching means 133 alongits length. In order that pressure applied to the column via thestretching means 133 does not cause buckling and bowing, a number ofcarpet engaging stablising means 134 are positioned along the length ofthe mounting structure. Each stablising means 134 includes a pair oftransversally spaced gripping heads 135 joined by a bridging element 136having a central collar or yoke 137 which sits over the elongated rodsto prevent lateral movement thereof. The collars 137 abut retentionmeans (not shown) on the mounting structure whereby the bridging element136 constitutes a transverse rung against which both the stretchingmeans 133 and a carpet holding means can bear during stretchingoperations.

FIGS. 7(a) to 7(e) illustrate the stages followed in the stretchingoperation. A length of carpet 151 is laid out along the area to becarpeted between walls or skirting boards 156 and 157. A mountingstructure 152 is assembled and laid on the carpet along its full length.Stretching means 153 is then positioned as seen in FIG. 7(a) and thecarpet stretched between the wall and the stretching means. As seen inFIG. 7(b) a carpet holding means 154 is then positioned adjacent thestretching means 153 which are then re-positioned further along themounting structure.

The carpet is then again stretched and the holding means repositioned asshown in FIG. 7(c). As seen in FIG. 7(d) the stretching means 153 isrepositioned at the end of the carpet run and after further stretchingthe holding means 154 can be removed as seen in FIG. 7(e). Theunstretched portion of carpet, 155 in FIGS. 7(a) and 7(b) and 158 inFIGS. 7(c) and 7(d), decreases as the process continues.

The stretching apparatus in accordance with this invention may be usedin numerous ways to stretch carpet in accordance with desirablepractices and with the required specifications. Preferably thestretching sub-frames or scaffold frames or modules are laid out andconnected to provide a mounting structure which extends across theentire length of the carpet being laid, even if such length is in excessof 50 meters.

For example if a pair of stretching means are utilised the carpet can befirst stretched across its entire length or across a substantialcomponent of the total length, and then further stretched by utilising asecond intermediate stretching means.

However it is preferred that a stretching means is used in associationwith holding means so that the carpet is uniformly and progressivelystretched by sequentially applying the stretching means, holding thestretched carpet in place with the holding means and then repeating thesteps with the stretching means advanced along the mounting structure.Furthermore, because of the degree of control provided by the presentinvention and the considerably broader head which may be usedeffectively with the present invention, the number of passes required tostretch a given width of carpet can be significantly reduced.

Equally it is possible in accordance with the present invention toutilise a fixed stretching means at the end of the carpet and to operatewith a pair of travelling stretching means, or with stretching meanscombined with holding means in the intermediate portions.

It will of course be realised that the above has been given only by wayof illustrative example of the invention and that all such modificationsand variations thereto as would be apparent to persons skilled in theart are deemed to fall within the broad scope and ambit of the inventionas defined in the following claims.

I claim:
 1. A carpet stretching assembly including:an elongatesubstantially two-dimensional mounting structure for positioning in astable configuration on a carpeted surface, said mounting structurecomprising a plurality of modules, each having a pair of substantiallyparallel side rails and a plurality of transverse cross members joiningsaid side rails, the modules being interconnectable end-to-end wherebythe side rails of interconnected modules constitute a pair oflongitudinally extending elongate strut members of said mountingstructure; anchoring means at one end of said mounting structure forpositioning against a wall surface for anchoring said mounting structurerelative to a carpet fixed to the floor adjacent the wall surface;releasable stretching means engageable with said mounting structure andoperable to stretch carpet in a longitudinal direction of said mountingstructure away from said anchoring means, said stretching means havingtransport means guided by said mounting structure and supporting saidstretching means for movement in said longitudinal direction along saidmounting structure, abutment means engageable with a transverse crossmember to prevent movement of said stretching means in a rearwarddirection towards said anchoring means and thereby locate saidstretching means relative to said mounting structure, a gripping headassembly for releasably gripping the carpet, and actuating means formoving said gripping head assembly relative to said abutment means,whereby upon actuation of said actuating means and engagement of saidabutment means with a cross member, carpet gripped by said gripping headassembly is stretched in a forward direction away from its point offixing to the floor adjacent the wall surface; and carpet holding meansengageable with said mounting structure intermediate said stretchingmeans and said anchoring means and operable to maintain carpet stretchedby said stretching means in a stretched condition when carpet gripped bysaid gripping head assembly is released, said carpet holding meanshaving, abutment means engageable with a transverse cross member toprevent movement of said carpet holding means in a rearward directiontowards said anchoring means and thereby locate said carpet holdingmeans relative to said mounting structure, and a gripping head assemblyfor releasably gripping the carpet.
 2. A carpet stretching assembly asclaimed in claim 1, wherein said stretching means straddles saidmounting structure and said transport means supports said stretchingmeans on said carpeted surface externally of said strut members.
 3. Acarpet stretching assembly as claimed in claim 2, wherein saidstretching means includes a frame supporting said actuating means, saidtransport means comprising a plurality of wheels mounted on said frame.4. A carpet stretching assembly as claimed in claim 3, wherein saidcarpet holding means includes transport means guided by said mountingstructure and supporting said carpet holding means for movement in saidlongitudinal direction.
 5. A carpet stretching assembly as claimed inclaim 4, wherein said mounting structure is constructed from aluminum.6. A carpet stretching assembly as claimed in claim 5, wherein saidgripping head assembly includes at least one gripping head having anarray of inclined spikes projecting downwardly therefrom.
 7. A carpetstretching assembly as claimed in claim 6, wherein said gripping headassembly includes at least three said gripping heads arranged such thatone said gripping head is positioned centrally of said mountingstructure and the other said gripping heads are respectively positionedtransversely on either side thereof.
 8. A carpet stretching assembly asclaimed in claim 6, wherein said actuating means includes a ratchetmechanism.
 9. A carpet stretching assembly as claimed in claim 6,wherein said actuating means includes a hydraulic jacking mechanism. 10.A carpet stretching assembly as claimed in claim 9, wherein the abutmentmeans for said stretching means is fixed to a cylinder of said hydraulicjacking mechanism.
 11. A carpet stretching assembly comprising:amounting structure having a pair of side rails interconnected by aplurality of transverse cross members; anchoring means disposed at oneend of said mounting structure for anchoring said mounting structureagainst a fixed surface relative to a carpet on a floor; and releasablestretching means engageable with said mounting structure and operable tostretch carpet in a direction away from said anchoring means, saidstretching means having transport means guided by said mountingstructure and supporting said stretching means for movement in saidlongitudinal direction, abutment means engageable with a transversecross member to prevent movement of said stretching means in a directiontowards said anchoring means, a gripping head assembly for releasablygripping the carpet, and actuating means for moving said gripping headassembly relative to said abutment means.
 12. A carpet stretchingassembly as claimed in claim 11, further comprising carpet holding meansengageable with said mounting structure intermediate said stretchingmeans and said anchoring means, and operable to maintain carpetstretched by said stretching means in a stretched condition when carpetgripped by said gripping head assembly is released, said carpet holdingmeans having, abutment means engageable with a transverse cross memberto prevent movement of said carpet holding means in a direction towardssaid anchoring means, and a gripping head assembly for releasablygripping the carpet.